1. Field of the Invention
The present invention relates to a method for inducing mutations in plants, and more particularly to a method for increasing the number of plants of a first species which exhibit a phenotype or characteristic normally associated with a different species.
2. Description of the Prior Art
The members of a given species of plant typically share a number of well-established physical characteristics associated with the genetic materials of their cells; these characteristics are known as phenotypes. However, it is well known that plants of a given species having one or more new and distinctive characteristics, generally referred to as sports or mutations, occur naturally as a small fraction of any plant population. For centuries, mutants have been selectively bred to produce new varieties or modifications of existing plants. In natural populations of plants, however, the frequency of mutations is generally considered to be less than 1 in 500,000, so that the selection of desirable mutants after such breeding is a slow and laborious process, particularly since it is well recognized that mutants exhibiting a desirable phenotype are rare, and progeny outputs are often low.
Several methods for increasing the occurrence of mutants in a population of a given species are well known; for example, the exposure of such a population to ionizing radiation. Such techniques, however, are typically subject to the drawbacks that the individually resulting mutants are generally weak, and must still be subjected to the time-consuming and labor-intensive techniques of isolation and selective breeding for a large number of generations, before a sufficient number of mutants possessing the new phenotype are obtained for use in outcrossing or agricultural growth.
Recombinant DNA and protoplast fusion techniques are potentially useful for producing new varieties of plants without isolation of mutants or selective breeding. The use of these techniques is subject to several drawbacks, however. First, these techniques are tedious and slow, requiring elaborate instrumentation involving a large number of chemical processes, and a substantial investment in the education and training of the personnel conducting the procedures. Presently, these techniques are very expensive and time consuming. Indeed, Applicant is aware of no reported instance of the inducement of a functional expression of a novel gene (phenotype) from one species of plant to a population of another species of plant, employing these genetic engineering techniques.